Breathing circuits are commonly utilized in the operating room of a medical facility to convey anesthesia or inspiratory gases from an anesthesia machine to a patient, and to route expiratory gases from the patient to the anesthesia machine for subsequent cleansing and processing of same.
At present, several varieties of breathing circuits are available. One type of breathing circuit of substantial prevalence, and of particular relevance to the present invention as described herein, is a unilimb breathing circuit, wherein examples of such unilimb breathing circuits may be seen with reference to U.S. Pat. No. 4,265,235 to Fukunaga, U.S. Pat. No. 5,404,873 to Leagre et al., and U.S. Pat. No. 6,439,231 to Fukunaga et al. Generally, and as disclosed in the aforementioned patents, unilimb breathing circuits typically comprise a corrugated outer expiratory tube coaxially arranged about a corrugated inner inspiratory tube; that is, a tube-within-a-tube configuration. As such, one end of the unilimb breathing circuit, commonly referred to as the patient end, receives a connector for adapting the unilimb breathing circuit to a face mask, endotracheal tube, or laryngeal tube connected to the patient. The opposing end of the unilimb breathing circuit, commonly referred to as the machine end, typically receives a manifold for adapting the unilimb breathing circuit to an anesthesia machine for requisite inspiratory and expiratory gas manipulation.
Specifically, the manifold functions to direct anesthetic inspiratory gases from the anesthesia machine through the inner inspiratory tube for subsequent patient inhalation. During patient exhalation, expiratory gases flow through the outer expiratory tube and are redirected by the manifold to a carbon dioxide absorber of the anesthesia machine for subsequent removal of carbon dioxide gases therefrom. The cleansed exhaled gases may then be routed back through the inspiratory tube for rebreathing by the patient in conjunction with freshly administered anesthetic inspiratory gases.
In addition to the ability of unilimb breathing circuits to effectively bi-directionally conduct inspiratory and expiratory gases, unilimb breathing circuits are further capable of warming inherently lower temperature anesthesia gases. Essentially, patient expired gases flowing through the outer expiratory tube warm the inherently cooler anesthesia gases flowing through the inner inspiratory tube.
However, as a result of the temperature differential between the inspiratory and expiratory gases, moisture carried within the expiratory gases begins to condense within the corrugations of the expiratory tube, resulting in significant accumulation of moisture therewithin. Although such moisture may provide the ancillary benefit of humidifying the upper respiratory track of the patient during inspiration of dry anesthetic inspiratory gases, the moisture-laden unilimb breathing circuit is typically discarded after its first use, as medical practitioners have been unable to devise a secondary application for the moisture accumulated therewithin.
Discarding the breathing circuit presents the obvious ramification of excess waste of medical supplies, especially in view of the number of medical procedures requiring administration of anesthesia gases, and thus, the use of breathing circuits. Unfortunately, the cost of such expensive medical supplies is often imparted to the patient, adding to an often already overwhelming medical bill.
However, excess use and waste of medical supplies is not limited to disposal of the breathing circuits alone. Following completion of an operation or similar procedure requiring the administration of anesthesia gases via the breathing circuit, the patient is then typically transported from the operating room to the post-anesthesia care unit (i.e., PACU), where the patient is administered fresh oxygen gas to counteract the sedative effects of the anesthesia gases. Prior to patient inhalation of the oxygen gas, however, the inherently dry oxygen gas, delivered via a central oxygen source, must first pass through a bottle of sterile water for purposes of humidifying same, wherein the oxygen gas flow rate is regulated via a conventional flow meter. The humidified oxygen gas is then conveyed to the patient via a second, new length of tubing (i.e., corrugated tubing) connected to a conventional face tent worn by the patient.
Although the above-referenced method provides for the requisite humidification of oxygen gas, it possesses inherent disadvantages that make its implementation highly inefficient and uneconomical. More specifically, the patient is now further responsible for payment of the additional corrugated tubing, the bottle of sterile water, and the associated nebulizer adapter, typically utilized to atomize inspiratory gases passing therethrough. Furthermore, because the oxygen gas must first be passed through the gas-permeable “barrier” of sterile water for humidification purposes (i.e., bottle of sterile water), a higher quantity or percentage of oxygen gas must be passed into the bottle of sterile water to yield an overall effective percentage of humidified oxygen gas suitable for patient inhalation. As such, the patient is also responsible for payment of seemingly unavoidable excess quantities of oxygen gas.
Additionally, in view of efforts to develop products and/or processes that materially contribute to the environmental restoration and/or maintenance of basic life-sustaining natural elements, and the more efficient utilization and conservation of energy resources, the above-discussed method of oxygen gas humidification significantly hinders such present environmental conservation efforts. Specifically, because the bottle of sterile water, corrugated tubing, nebulizer, and associated adaptors and/or accessories, are discarded after first use, millions of gallons of precious water, and valuable petroleum resources utilized to manufacture the plastic tubing, bottle, nebulizer, and the like, are consumed to ensure the sustained provision of such medical supplies.
Therefore, it is readily apparent that there is a need for an apparatus and method for humidification of inspired gases, wherein said apparatus and method utilizes condensed expiratory gases deposited within a breathing circuit to humidify oxygen gas for subsequent patient inhalation, and wherein said apparatus and method functions to effectively eliminate dependency upon prior art methods of humidification, wasteful utilization of bottles of sterile water, corrugated tubing, nebulizer adapters and excess consumption of oxygen gas; thus, effectuating a cost savings for the patient and contributing to overall environmental conservation efforts.